A comedy act in earlier days often included a part where one of the comedians would hit the others over the head with a soft object.

VOA: special.2009.11.29

"Jeff,you have always been a man of a soft and generous heart.

VOA: special.2010.04.24

The canyon walls are made of a soft rock called tuff.

VOA: special.2010.07.05

After thousands of years the ash became a soft rock.

VOA: special.2010.07.05